Using Tags :

The NE1 Web Builder has made it easy to personalize your newsletter by including special “tags” in your message. These tags are “dynamic” – meaning they will change “on the fly” as the newsletter is sent. For example, using the {%firstname%} tag in either the message, subject, or footer will result in the newsletter finding the first name’s of all subscribers on your list and automatically entering their names into their newsletter. This is a great way to personalize the newsletters. The {%email%} tag is also available to include the recipients email address.